SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '71377a5aa567b99f264433730fc1e5d5b80957490f43d6a8dccf3e7042e77508' 
  AND token = '66LNH/WbcuXpdnfsZJR5zkYIXncTjFoH3Gd0UAU0EOs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}